<h3>@../index</h3>
{{#each list}}
    <dl>
        <dt>年级-{{@index}}</dt>

        {{#each .}}
            <dd>
                Grade:{{@../index}},teacher:{{this.teacher}},number:{{this.number}}
            </dd>
        {{/each}}

    </dl>
{{/each}}

<hr>
<h3>../../</h3>
{{#each list as |grade|}}
    <dl>
        <dt>Grade:{{@index}}</dt>
        {{#each grade as |info|}}
            <dd>
                {{@../index}},
                {{@index}},
                Teacher:{{info.teacher}},
                Number:{{info.number}},
                Title:{{../../title}},
                Length:{{../../list.length}}
            </dd>
        {{/each}}

    </dl>
{{/each}}

<hr>
<h3>@key / .</h3>
{{#each list}}
    <dl>
        <dt>Grade:{{@index}}</dt>
        {{#each .}}
           <dd>{{@key}}:{{this.teacher}}</dd>
        {{/each}}
    </dl>
{{/each}}

<hr>
<h3>循环空数据</h3>
{{#each emptyList}}
    <p>{{.}}</p>
{{else}}
    <b>No data</b>
{{/each}}

<hr>
<h3>log</h3>
{{log haha}}